how do i get the hair particles to stand up straight
While selecting the particle emitter mesh, go to the properties tab to the particle settings and under "render", check the box which says rotation.  Now you can go over to the wheat object and rotate it (in object mode) until the hair particles on the other object are standing straight up.  You will probably be rotating it by a 90 degree angle.

Let it be known, that in order for this to work correctly, the wheat has to have its origin at the bottom of its stem.